Organic solvent based adhesives have been used for many years for joining objects made from PVC (polyvinyl chloride), CPVC (chlorinated polyvinyl chloride), ABS (acrylonitrile-butatdiene-styrene) and other thermoplastics. In use, the organic solvent partially dissolves or at least softens the surfaces to be joined, thereby achieving an intimate bond between these surfaces when the organic solvent evaporates. Normally, a small amount of thermoplastic resin, the same as or similar to the thermoplastic to be joined, is dissolved in the solvent, thereby producing a “solvent cement.” Additionally or alternatively, an acrylic resin can be included in the solvent cement, as acrylics adhere well to all three common plastics, i.e., PVC, CPVC and ABS. See, for example, U.S. Pat. No. 5,073,615 and U.S. Pub. App. No. 2006/0252865, the disclosures of which are incorporated herein by reference.
Before applying a solvent cement, the surfaces to be joined are normally bathed with a primer comprising a solvent for the plastic to be bonded. This also partially dissolves or at least softens these surfaces, thereby allowing the solvent cement to penetrate more effectively for producing a better adhesive bond. If desired, these surfaces can be cleaned before application of the primer to remove any dirt and/or grease that might be present, although this is usually unnecessary.
Many building codes require that plastic piping systems made with solvent cements be primed before application of the solvent cement and further that the primer include an intense colorant, usually purple, to facilitate visual confirmation that the primer and solvent cement have been properly applied. Unfortunately, such purple primers often create unsightly stains on unintended surfaces such as floors, countertops, skin, clothing, etc., as a result of the primer spilling and/or falling off the applicator with which it is applied.